• Title/Summary/Keyword: Contact condition

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Dynamic Contact of a Cantilever Beam with Rigid Wall Condition (강체벽과 충돌하는 한단이 고정된 외팔보의 진동)

  • Park, Nam-Gyu;Jang, Young-Ki;Kim, Jae-Ik;Kim, Kyu-Tae
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.436-439
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    • 2005
  • Dynamic contact of a cantilever beam with Sap at the end is discussed. The gap in a structure induces dynamic contact, and the contact problem is always accompanied by inequality constraints which mean that the solution of the structure with contact condition should satisfy variational inequality. Inequality, but, can be reduced to equality condition considering convex penalty function. In this paper, formulation of a beam with contact is derived using quasi convex penalty function. General coordinate solution which is needed to increase computational efficiency is applied. Nonlinear behavior of a beam with rigid and elastic contact condition was discussed.

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Relationship between Contact Resistance and Tribological Behavior in Boundary Lubrication (경계윤활에서 접촉 저항과 트라이볼로지 특성의 상관 관계에 관한 연구)

  • 이홍철;김대은
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2000.06a
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    • pp.76-83
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    • 2000
  • Boundary lubrication condition arises in most lubricated systems, especially during motion reversals and start up phase of operation. In this work electric contact resistance variations with respect to sliding conditions under lubrication is investigated The motivation was to improve the understanding of the contact condition in the boundary lubrication regime. It is shown that electrical contact resistance is sensitive to sliding speed and surface condition of the specimens. Also, phenomena such as run-in during the initial phase of sliding and lubricant pile up near the sliding pin could be observed. The results of this work will aid in better understanding of the metal to metal contact condition in lubricated systems.

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Relationship between Contact Resistance and Tribological Behavior in Boundary Lubrication (경계윤활에서 접촉 저항과 트라이볼로지 특성의 상관 관계에 관한 연구)

  • 이홍철;김대은
    • Tribology and Lubricants
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    • v.16 no.5
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    • pp.381-388
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    • 2000
  • Boundary lubrication condition arises in most lubricated systems, especially during motion reversals and start up phase of operation. In this work electric contact resistance variations with respect to sliding conditions under lubrication is investigated. The motivation was to improve the understanding of the contact condition in the boundary lubrication regime. It is shown that electrical contact resistance is sensitive to sliding speed and surface condition of the specimens. Also, phenomena such as run-in during the initial phase of sliding and lubricant pile up near the sliding pin could be observed. The results of this work will aid in better understanding of the metal to metal contact condition in lubricated systems.

A hysteresis model for soil-water characteristic curve based on dynamic contact angle theory

  • Liu, Yan;Li, Xu
    • Geomechanics and Engineering
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    • v.28 no.2
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    • pp.107-116
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    • 2022
  • The steady state of unsaturated soil takes a long time to achieve. The soil seepage behaviours and hydraulic properties depend highly on the wetting/drying rate. It is observed that the soil-water characteristic curve (SWCC) is dependent on the wetting/drying rate, which is known as the dynamic effect. The dynamic effect apparently influences the scanning curves and will substantially affect the seepage behavior. However, the previous models commonly ignore the dynamic effect and cannot quantitatively describe the hysteresis scanning loops under dynamic conditions. In this study, a dynamic hysteresis model for SWCC is proposed considering the dynamic change of contact angle and the moving of the contact line. The drying contact angle under dynamic condition is smaller than that under static condition, while the wetting contact angle under dynamic condition is larger than that under static condition. The dynamic contact angle is expressed as a function of the saturation rate according to the Laplace equation. The model is given by a differential equation, in which the slope of the scanning curve is related to the slope of the boundary curve by means of contact angle. Empirical models can simulate the boundary curves. Given the two boundary curves, the scanning curve can be well predicted. In this model, only two parameters are introduced to describe the dynamic effect. They can be easily obtained from the experiment, which facilitates the calibration of the model. The proposed model is verified by the experimental data recorded in the literature and is proved to be more convenient and effective.

Analysis for the dynamic responses of pantograph-overhead contact line coupled system by using a condition monitoring system (상태감시시스템을 이용한 팬터그래프-전차선로 동특성 분석에 관한 연구)

  • Cho, Yong-Hyeon;Park, Young;Lee, Ki-Won;Kwon, Sam-Young;Park, Hyun-June
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.04a
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    • pp.778-781
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    • 2008
  • The aim of this paper is to analyze the dynamic responses of pantograph-overhead contact line coupled system by using a condition monitoring system. The monitoring items are strain, vertical displacement and acceleration of a contact wire. Both strain and vertical displacement in the contact wire depends on uplift force and train velocity. Measurement of acceleration shows that the passage of the pantograph gives an impact force to a hard point on a contact wire.

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Influence of Process Condition on Contact Resistance in WSix Deposition (WSix 증착에서 공정조건이 contact 저항에 미치는 영향)

  • 정양희;강성준;강희순
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2002.05a
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    • pp.279-282
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    • 2002
  • In this paper, we discuss influence of process condition on contact resistance in WSix deposition process. In the WSix deposition process, we confirmed that word line to bit line contact resistance(WBCR) due to temperature of word line WSix deposition among various process condition split experiment. RTP treatment, d-poly ion implantation dose and thickness was estimated a little bit influence on contact resistance. Also, life time of shower head in the process chamber for WSix deposition related to contact resistance. The results obtained in this study are applicable to process control and electrical characteristics for high reliability and high density DRAM's.

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REMARKS ON LEVI HARMONICITY OF CONTACT SEMI-RIEMANNIAN MANIFOLDS

  • Perrone, Domenico
    • Journal of the Korean Mathematical Society
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    • v.51 no.5
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    • pp.881-895
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    • 2014
  • In a recent paper [10] we introduced the notion of Levi harmonic map f from an almost contact semi-Riemannian manifold (M, ${\varphi}$, ${\xi}$, ${\eta}$, g) into a semi-Riemannian manifold $M^{\prime}$. In particular, we compute the tension field ${\tau}_H(f)$ for a CR map f between two almost contact semi-Riemannian manifolds satisfying the so-called ${\varphi}$-condition, where $H=Ker({\eta})$ is the Levi distribution. In the present paper we show that the condition (A) of Rawnsley [17] is related to the ${\varphi}$-condition. Then, we compute the tension field ${\tau}_H(f)$ for a CR map between two arbitrary almost contact semi-Riemannian manifolds, and we study the concept of Levi pluriharmonicity. Moreover, we study the harmonicity on quasicosymplectic manifolds.

Cytotoxicity of target cell against Naegleria fowleri under non-contact condition (비접촉 조건에서의 Naegleria fowleri에 의한 표적세포의 세포독성)

  • Kang, Changgeun;Hong, Il-Hwa;Kim, Jong-Hyun
    • Korean Journal of Veterinary Service
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    • v.42 no.4
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    • pp.169-175
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    • 2019
  • Naegleria fowleri, a pathogenic free-living amoeba, leads to a fatal infection known as primary amebic meningoencephalitis (PAM) in human and animals. PAM is an acute, fulminant, necrotizing, and hemorrhagic disease that leads to death in approximately seven days. In this study, we investigate the cytotoxicity of target cells and the secreted molecules of N. fowleri under the non-contact condition. The target cell (U87MG cell) treated with N. fowleri lysates showed no morphological changes and no cytotoxicity. By contrast, the U87MG cells co-cultured with N. fowleri trophozoites under the non-contact condition induced morphological changes and reduction in number. When U87MG cells were co-cultured with N. fowleri trophozoites under the non-contact condition for 30 min, 2 hr, and 4 hr, the levels of cytotoxicity of target cells were 32.3, 35.5, and 37.8%, respectively. Particularly, when the ratio of amoeba to target cells is 10 to 1, the level of cytotoxicity of target cells was 49.7% at 30 min. To show the proteins secreted from N. fowleri under the non-contact condition, we carried out 2D electrophoresis and observed 6 major proteins. Finally, these results suggest that the molecules released from N. fowleri under the non-contact condition induce the cell death and this process is an important step in pathogenesis of N. fowleri.

Dynamic Analysis of a High-speed Wheel Moving on an Elastic Beam Having Gap with the Consideration of Hertz Contact (간격이 있는 탄성 보 위를 고속 주행하는 바퀴의 Hertz 접촉을 고려한 동역학적 해석)

  • Lee, Ki-Su;Kim, Seok-Seung
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.22 no.3
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    • pp.253-263
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    • 2012
  • With the local Hertz deformation on the contact point, the dynamic contact between a high-speed wheel and an elastic beam having a gap is numerically analyzed by solving the whole equations of motion of the wheel and the beam subjected to the contact condition. For the stability of the time integration the velocity and acceleration constraints as well as the displacement constraint are imposed on the contact point. Especially the acceleration contact condition on the gap is formulated, and it is demonstrated that the contact force variation computed by the velocity contact constraint or by the acceleration contact constraint agrees well with that computed by the displacement contact constraint. The numerical examples show that, when the wheel passes on the gap, the solution is governed by the stiffness of the local Hertzian deformation.